On 04/03/2016 09:31 AM, Nicklas Karlsson wrote: >> Lets say there are three different G Code files, A, B and C. >> >> In file A, the coordinates are such: X x.x Y x.x >> >> In file B, the coordinates are such: X x.xx Y x.xx >> >> In file C, the coordinates are such: X x.xxx Y x.xxx >> >> For simplicity's sake, no Z axis and the units are inches. >> >> Using file A for example, with the coordinates only given with 0.1" >> precision, what exactly does the controller do? Does it actually work >> to 0.1" precision or does it work to moreprecision, vis-a-vis when >> making moves? >> >> Is file C, with precision to three decimal places the standard precision >> in controllers, or do we just use three decimal places in the G Code >> because it's good enough for gummint workand the controller can actually >> make more precise moves (dependent of course on the machine, the >> mechanics and the electronics)? >> >> Mark > Machine resolution depend on for example: Movement for each step or micro > step for a stepper motor. Resolution of encoder for a motor with encoder. > Resolution may be degraded from this but if number of encoder pulses is sent > back to linuxcnc this should be the maximum resolution. > > > Then it might be worth noting: Float point according to IEEE 754 is 23 bits > and double 53 bits regardless of decimal point position. Float work great for > values read from an analog to digital converter since number of significant > bits will be the same regardless of decimal point position which vary > depending on what value is representing. > > For float it may also be worth noting values will be closer together for > small values. > > Then unit is changed decimal point will be moved and there will be some > rounding errors so then using for machine control the question between float > and double will be. Is 23 bits resolution enough? Or is 53 bits resolution > needed? Are there any difference in computational speed? > > > Regards Nicklas Karlsson
I get that, but let's assume the theoretically perfect machine. Disregard the shortcomings of the stepper/drive, servo/drive, or any slop and inaccuracy that would exist in the typical machine hardware like bearings, etc. Just the controller. If the G Code commands a straight line movement from X 0.0 Y 0.0 to X 1.0 Y 0.0, disregarding accel and decel for the moment, is the precision/resolution of that move (in inches as before) 0.1", 0.01", 0.001" or greater? Mark ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
